First round of removing title attributes.
Fix merge conflict.
Second round of removing title attributes.
_s: Simplify header image example markup.

`get_header_image()` will return the boolean false or an empty string if
there is no header image. Both will be evaluated as false by the if
statement.

Related: http://core.trac.wordpress.org/ticket/25156
_s: Simplify header image markup in admin appearance page.
Merge branch 'master' of https://github.com/davidakennedy/_s into titles

Conflicts:
	image.php
	inc/custom-header.php
	searchform.php
_s: Update pot file to reflect recent changes in public strings.